Biomedical subjects

Ying Liu

Publications and source records attributed to Ying Liu.

At least 325 records · Page 18Linked to original sources

PubMed2004

Beta2-adrenergic receptor gene polymorphism in Chinese Northern asthmatics.

OBJECTIVE: To investigate whether the polymorphisms of beta2-adrenergic receptor (beta2-AR) at position 16, 27, 164 are associated with asthma in Northern Chinese subjects. METHODS: Genomic DNA was collected from unrelated Northern Chinese population of Han ethnicity, including 125 unrelated asthmatic individuals and 96 healthy controls. Beta2-AR genes at position 16, 27, 164 were amplified by using restriction fragment length polymorphism (RFLP) and allelic specific polymerase chain reaction methods. All asthmatics had their serum IgE (total and specific) antibody or skin-prick test measured, bronchial reactivity to methacholine (Mch) and bronchial reversibility by beta2-agonist evaluated. RESULTS: (1) The frequency of Gly 16 homozygous was significantly higher in the asthmatic group than that in healthy controls (22.4% vs. 8.3%, P < 0.05), OR was 2.9 with 95% CI 1.26-6.78. The proportion of Gly 16 allele was also higher in asthmatics than that in control (0.46 vs. 0.36, P < 0.05); Gly16 homozygous was not independently associated with asthma pathogenesis (P = 0.21, OR 0.42 with 95% CI 0.11-1.61). (2) Of 51 night attack patients, 18 carrying Gly16 homozygosity, if compared with 10 of 74 nonnocturnal asthmatics carrying this genotype, there was significant difference between these two groups (35.3% vs. 13.5%, P < 0.01). (3) The average dose of PD20-Mch was significantly lower in patients carrying Gln 27 homozygous than those carrying homozygous Glu 27 and Gln/Glu 27 heterozygous (0.2 +/- 0.3, 1.6 +/- 0.8, and 2.1 +/- 3.0 micromol/L, P < 0.05). CONCLUSION: Beta2AR gene polymorphisms might confer susceptibility to asthma in Chinese Northern patients. Beta2-AR gene, coordinated with other candidate loci, plays a role in the development of asthma.

Adult↗

PubMed2004

[Immunogenicity analysis of HIV vaccine based on replicating vaccinia virus Tiantan vector].

OBJECTIVE: To investigate the immunogenicity of HIV vaccine vTKgpe based on Vaccinia Virus Tiantan vector in mice and rabbits. METHODS: Mice were inoculated with HIV vaccine vTKgpe by intramuscular (i.m.), intradermal (i.d.) or subcutaneous (s.c.) injections. Blood sample were collected every week, and then antibodies against HIV and vaccinia virus vector were detected. At week 4, some mice were killed and cellular immune responses were examined by flow cytometer. Additionally two rabbits were vaccinated subcutaneously, blood sample were tested as done with mice. RESULTS: In mice i.m. and s.c. groups, HIV specific antibodies emerged at week 2 and declined at week 4. Antibodies against vector elevated rapidly at week 4, and potentially affected HIV specific antibody detection. Cellular immune responses were only detected in s.c. group. Serum of rabbit showed that anti-HIV antibody appeared at week 2 and maintained for several weeks. CONCLUSION: Vaccine vTKgpe innoculated by i.m. and s.c routes inclined to induce humoral immune responses in mice, but in i.d. group, inclined to induce cellular immune responses. Response to the recombinant vaccinia virus was more sensitive in rabbit than in mice.

AIDS Vaccines↗

PubMed2004

[Chiral separation of beta-receptor blockers and analogs on novel norvancomycin-bonded chiral stationary phase].

Enantiomeric separation of racemates of 8 beta-receptor blockers and analogs was performed on a novel norvancomycin-bonded chiral stationary phase (NVC-CSP) in polar organic mode using high performance liquid chromatography. The influences of mobile phase composition, acetic acid and triethylamine contents, temperature and flow rate on enantiomeric separation were studied. It was found experimentally that with the increase of the fraction of methanol in the mobile phase, the same tendency was found for all the chiral solutes studied, i. e., the decrease in retention factor (kappa) and the increase in the enantioselectivity factor (alpha). With the increase of column temperature, most solutes were less retained and the alpha value decreased accordingly. Better resolutions were obtained at lower flow rates as a result of the minimization of the resistance to mass-transfer. Better separation results and suitable retentions for most solutes were obtained when a mixture of acetonitrile-methanol-acetic acid-triethylamine (60: 40: 0.4: 0.2, v/v) was used as mobile phase at a flow rate of 0.6 mL/min, and the column temperature was set at 25 degrees C. Conclusions can be drawn from the experimental data that pi-pi complexation, dipole-stacking interactions were engaged in the process of enantiomeric separation, while hydrogen bonding interaction between solutes and CSP was commonly non-enantioselective, although it was mainly responsible for the increased retention in the acetonitrile-predominant mobile phases.

Adrenergic beta-Agonists↗

PubMed2004

[The depolarization characteristic of quartz depolarizer in UV-VUV spectral region].

The quartz depolarizer consisting of two wedge-shaped quartz crystals was designed based on the Lyot depolarizer. The quartz depolarizer is used to reduce the polarization response of spectral instruments. The residual degree of polarization of the quartz depolarizer was derived by the method of matrix optics, so the variation regularity of its depolarization characteristic was analysed concerning its center thickness and the status of the incident radiation in the UV-VUV spectral range. Its depolarization effect was obvious for the radiation with some spectral bandwidth. Also, the depolarization characteristic of the quartz depolarizer was studied experimentally with 1-meter Seya-Namioka UV-VUV spectrometer, using LiF crystals as the polarizer and analyzer. The residual degree of polarization of the quartz depolarizer was less than 1%. Both the theoretical analysis and experimental results show that the quartz depolarizer we designed is appropriate to the spectral measurement with high accuracy.

English Abstract↗

PubMed2004

[Spectral evidences for aggregation of sulfonated naphthalocyanine zinc (II) and cobalt (II)].

When the naphthalocyanines were sulfonated to give sulfonated naphthalocyanine cobalt (II) and sulfonated naphthalocyanine zinc (II), enhanced aggregation tendency was observed. The Q band of the fluorescence emission spectra and electronic absorption spectra for sulfonated naphthalocyanine zinc (II) and sulfonated naphthalocyanine cobalt (II) in the solutions of DMF and ethanol showed that the excimer or the aggregation form coexists with the monomer, that the aggregation form dissociates into its monomer when the excimer releases a photon or the ground aggregation form absorbs a photon, and that mirror symmetry exists between the fluorescence emission spectrum of the excimer and the electronic absorption spectrum of the corresponding ground aggregation form. There is a red shift for the excimer in the fluorescence emission spectrum and a blue shift for the aggregation form in the electronic absorption spectrum of the Q band. The quenching effect in fluorescence emission spectrum is large when the concentration of sulfonated naphthalocyanine cobalt (II) is high.

Cobalt↗

PubMed2004

BG01V: a variant human embryonic stem cell line which exhibits rapid growth after passaging and reliable dopaminergic differentiation.

PURPOSE: To explore a karyotypically abnormal variant human embryonic stem cell (hESC) line, BG01V, as a potential model for studies of dopaminergic neuronal differentiation. METHODS: The properties of BG01V cells were compared to those of normal BG01 cells using immunocytochemistry, RT-PCR, focused microarrays and in vitro differentiation, including dopaminergic differentiation, by culturing with the stromal cell line PA6. RESULTS: Despite the karyotypic abnormality (49, +12, +17 and XXY), undifferentiated BG01V cells expressed pluripotent ESC markers similar to BG01 cells, and retained the ability to differentiate into cell types characteristic of all three germ layers. When co-cultured with the stromal cell line PA6, BG01V cells differentiated into dopaminergic cells which exhibited properties similar to those of mature dopaminergic neurons. CONCLUSIONS: BG01V cells were easier to maintain in culture than karyotypically normal BG01 cells and can be used as an alternative pluripotent hESC type for in vitro developmental studies.

Blotting, Northern↗

PubMed2004

[Dynamic pattern of gene expression in rat hearts responding to transient ischemia/reperfusion detected by cDNA microarray and cluster analysis].

OBJECTIVE: To analyze the pattern of gene expression programs during rat myocardial ischemia/reperfusion at multiple time points. METHODS: Rat model of myocardial ischemia/reperfusion was established by repeating the occlusion and relaxation of left coronary artery. cDNA microarray was used to analyze the pattern of gene expression programs in rat myocardium at 1, 3, 6, 12, 24 hours after reperfusion. SOM cluster analysis was used to identify different cluster of genes in which each cluster had similar expression pattern. RESULTS: Altogether 75, 779, 205, 155, and 166 genes were differentially expressed at 1, 3, 6, 12, 24 hours after the reperfusion respectively. Clusters analysis identified 12 clusters of genes in which each cluster had similar expression pattern. CONCLUSION: Analysis of gene expression pattern revealed sequential induction of subsets of genes that characterize each response.

Animals↗

PubMed2004

[Screen selection of target genes regulated by HSF1 in heat shock response from myocardium of gene knockout mice].

OBJECTIVE: To screen select target genes regulated by heat shock transcription factor 1 (HSF1 ) in heat shock response from myocardium of HSF1 gene knockout mice using cDNA chip. METHODS: HSF1 knockout mice were subjected to heat shock treatment (42 degrees C for 15 minutes, and recovered for 3 hours), and cDNA chip containing 15 000 mouse cDNAs were employed to investigate the expression of genes regulated by HSF1 in the myocardium. Then 4 of the differentially expressed genes in the myocardium of HSF1 knockout mice were further confirmed by RT-PCR. The promoter regions of the differentially expressed genes were analysed by TESS software to find HSE. RESULTS: Three hundred and ninety-eight genes were down - regulated in the myocardium of HSF1 knockout mice in heat shock response,with 173 known. Whereas 641 genes were up-regulated in the myocardium, with 235 known. The 5 down-regulated genes and 6 up-regulated ones were shown to contain HSE in their promoter regions. CONCLUSION: In heat shock response, expression of multiple genes is regulated directly or indirectly by HSF1.

Animals↗

PubMed2003

Kruppel-like factor 4 (KLF4) represses histidine decarboxylase gene expression through an upstream Sp1 site and downstream gastrin responsive elements.

Histidine decarboxylase (HDC) is the enzyme that catalyzes the conversion of histidine to histamine, a bioamine that plays an important role in allergic responses, inflammation, neurotransmission, and gastric acid secretion. Previously, we demonstrated that gastrin activates HDC promoter activity in a gastric cancer (AGS-E) cell line through three overlapping downstream promoter elements. In the current study, we used the yeast one-hybrid strategy to identify nuclear factors that bind to these three elements. Among eight positives from the one-hybrid screen, we identified Kruppel-like factor 4 (KLF4) (previously known as gut-enriched Kruppel-like factor (GKLF)) as one factor that binds to the gastrin responsive elements in the HDC promoter. Electrophoretic mobility shift assays confirmed that KLF4 is able to bind all three gastrin responsive elements. In addition, transient cotransfection experiments showed that overexpression of KLF4 dose dependently and specifically inhibited HDC promoter activity. Regulation of HDC transcription by KLF4 was confirmed by changes in the endogenous HDC messenger RNA by KLF4 small interfering RNA and KLF4 overexpression. We further showed that KLF4 inhibits HDC promoter activity by competing with Sp1 at the upstream GC box and also independently by binding the three downstream gastrin responsive elements. Taken together, these results indicate that KLF4 can act to repress HDC gene expression by Sp1-dependent and -independent mechanisms.

DNA-Binding Proteins↗

PubMed2003

Allele frequencies of single nucleotide polymorphisms (SNPs) in 40 candidate genes for gene-environment studies on cancer: data from population-based Japanese random samples.

Knowledge of genetic polymorphisms in gene-environment studies may contribute to more accurate identification of avoidable risks and to developing tailor-made preventative measures. The aim of this study was to describe the allele frequencies of single nucleotide polymorphisms (SNPs) of select genes, which may be included in future gene-environment studies on cancer in Japan. SNP typing was performed on middle-aged Japanese men randomly selected from the general population in five areas of Japan. We genotyped and calculated allele frequencies of 153 SNPs located on 40 genes: CYP1A1, CYP1B1, CYP2C9, CYP2C19, CYP2E1, CYP17A1, CYP19A1, AHR, ESR1, ESR2, ERRRG, PGR, EPHX1, EPHX2, HSD17B2, HSD17B3, GSTM2, GSTM3, GSTT2, GSTP1, NAT1, NAT2, COMT, ADH1A, ADH1B, ADH1C, ALDH2, NOS2A, NOS3, IL1A, IL1B, OGG1, NUDT1 [MTH1], DRD2, DRD3, DRD4, SLC6A4, NR3C1 [GCCR], MTHFR, and NQO1. In the present study, the Japanese allele frequencies were verified by using nationwide population samples.

Alleles↗

PubMed2003

Resonance light scattering imaging detection of proteins with alpha,beta,gamma,delta-tetrakis(p-sulfophenyl)porphyrin.

A resonance light scattering (RLS) imaging technique was introduced to measure the light scattering of aggregation species induced by proteins, and thus a method of detecting proteins in the range of picograms was proposed. In acidic medium, J-aggregation of alpha,beta,gamma,delta-tetrakis(p-sulfophenyl)porphyrin (TPPS(4)) in the presence of proteins occurs, resulting in strong RLS signals characterized at 490 nm. Under the excitation of a 488-nm light beam of argon ion laser source, the scattered light of single J-aggregation species could be observed with a common microscope, and the images could be captured with a cooled charge-coupled device camera. Data analysis for the digital images showed that the counts of aggregate species in the detection focus plane are proportional to the concentration of proteins in picograms. When 1.0 x 10(-7)M TPPS(4) was employed, 0.01-210 ng/ml bovine serum albumin and human serum albumin could be detected with limits of detection lower than 10 pg/ml (3 sigma). Three human blood serum samples were satisfactorily detected with relative standard deviations lower than 3.04%.

Animals↗

PubMed2003

Biosynthesis, purification, and substrate specificity of severe acute respiratory syndrome coronavirus 3C-like proteinase.

The 3C-like proteinase of severe acute respiratory syndrome (SARS) coronavirus has been proposed to be a key target for structural-based drug design against SARS. In order to understand the active form and the substrate specificity of the enzyme, we have cloned, expressed, and purified SARS 3C-like proteinase. Analytic gel filtration shows a mixture of monomer and dimer at a protein concentration of 4 mg/ml and mostly monomer at 0.2 mg/ml, which correspond to the concentration used in the enzyme assays. The linear decrease of the enzymatic-specific activity with the decrease of enzyme concentration revealed that only the dimeric form is active and the dimeric interface could be targeted for structural-based drug design against SARS 3C-like proteinase. By using a high pressure liquid chromatography assay, SARS 3C-like proteinase was shown to cut the 11 peptides covering all of the 11 cleavage sites on the viral polyprotein with different efficiency. The two peptides corresponding to the two self-cleavage sites are the two with highest cleavage efficiency, whereas peptides with non-canonical residues at P2 or P1' positions react slower. The P2 position of the substrates seems to favor large hydrophobic residues. Secondary structure studies for the peptide substrates revealed that substrates with more beta-sheetlike structure tend to react fast. This study provides a basic understanding of the enzyme catalysis and a full substrate specificity spectrum for SARS 3C-like proteinase, which are helpful for structural-based inhibitor design against SARS and other coronavirus.

Catalysis↗

PubMed2003

Suppressive effects of BmK IT2 on nociceptive behavior and c-Fos expression in spinal cord induced by formalin.

In this study, the suppressive effects of BmK IT2, a kind of Na+ channel-specific modulator from the venom of the scorpion Buthus martensi Karsch, on biphasic nociceptive behavior in rats and c-Fos expression in rat spinal cord induced by formalin were investigated. Fifty microliters of 2.5% formalin were subcutaneously injected into the rat hind paw; 0.1 and 1 microg doses of BmK IT2 were subcutaneously administered into the rat ipsilateral hind paw 1 min before or 10 min after formalin injection individually, and the number of flinches per 5 min was counted. The detection of c-Fos expression induced by formalin in either the absence or the presence of BmK IT2 was carried out with the ABC method. Biphasic nociceptive behavior in rats was significantly suppressed by pretreatment with BmK IT2. No. of flinches/5 min in the second phase was also decreased by posttreatment with BmK IT2. In addition, c-Fos expression induced by formalin was significantly inhibited in all laminae of L4-5 spinal cord by pre- or posttreatment with BmK IT2. The suppression of BmK IT2 in the first- and second-phase behaviors may be attributed to the anesthesia of the toxin toward nociceptors and primary afferents and its selective modulation of tetrodotoxin-resistant Na+ currents of dorsal root ganglion neurons, respectively. In addition, the nonparallel suppression of BmK IT2 on flinch behavior and c-Fos expression induced by formalin may be ascribed to the different activity patterns of afferent fibers and central neurons.

Animals↗

PubMed2003

A "slide-back" mechanism for the initiation of protein-primed RNA synthesis by the RNA polymerase of poliovirus.

Poliovirus RNA replication is initiated when a molecule of UMP is covalently linked to the hydroxyl group of a tyrosine in the terminal protein VPg. This reaction can be reproduced in vitro with an assay that utilizes two purified viral proteins, RNA polymerase 3Dpol and viral protein 3CDpro, synthetic VPg, UTP, and Mg2+. The template for the reaction is either poliovirus RNA or transcripts of a small RNA hairpin, termed cre(2C), located in the coding sequence of protein 2CATPase. The products of the reaction are VPgpU and VPgpUpU, the primers used by 3Dpol for RNA synthesis. With mutant template RNAs in this assay we determined the precise initiation site. Our results indicate that 1) 3Dpol does not possess strict specificity toward the nucleotide it links to VPg, 2) A-5 of the conserved 1GXXXAAAXXXXXXA14 sequence in the loop is the template nucleotide for the linkage of both the first and second UMPs to VPg, 3) VPgpUpU is synthesized by a "slide-back" mechanism, and 4) A-6 provides specificity to the reaction during the slide-back step and also modulates the uridylylation reaction. In additional experiments we determined the effect of mutations in the 5AAA7 sequence of cre(2C) on viral growth, RNA replication, and on the activity of the 2CATPase protein. Furthermore, we observed that the spacing between G-1 and A-5 and the size of the loop affect the yield but not the nature of the VPg-linked products.

Amino Acid Sequence↗

PubMed2003

Identification of a novel integrin alpha 6 beta 1 binding site in the angiogenic inducer CCN1 (CYR61).

The angiogenic inducer CCN1 (cysteine-rich 61, CYR61), a secreted matricellular protein of the CCN family, is a ligand of multiple integrins, including alpha 6 beta 1. Previous studies have shown that CCN1 interaction with integrin alpha 6 beta 1 mediates adhesion of fibroblasts, endothelial cells, and smooth muscle cells, as well as migration of smooth muscle cells. Recently, we have reported that CCN1-induced tubule formation of unactivated endothelial cells is also mediated through integrin alpha 6 beta 1. In this study, we demonstrate that human skin fibroblasts adhere specifically to the T1 sequence (GQKCIVQTTSWSQCSKS) within domain III of CCN1, and this process is blocked by anti-alpha 6 and anti-beta 1 monoclonal antibodies. Alanine substitution mutagenesis of the T1 sequence further defines the sequence TTSWSQCSKS as the critical determinant for mediating alpha 6 beta 1-dependent adhesion. Soluble T1 peptide specifically inhibits fibroblast adhesion to CCN1 in a dose-dependent manner. Furthermore, T1 also inhibits cell adhesion to other alpha 6 beta 1 ligands, including CCN2 (CTGF), CCN3 (NOV), and laminin, but not to ligands of other integrins. In addition, T1 specifically inhibits alpha 6 beta 1-dependent tubule formation of unactivated endothelial cells in a CCN1-containing collagen gel matrix. To confirm that T1 binds integrin alpha 6 beta 1 directly, we perform affinity chromatography and show that integrin alpha 6 beta 1 is isolated from an octylglucoside extract of fibroblasts on T1-coupled Affi-gel. Taken together, these findings define the T1 sequence in CCN1 as a novel binding motif for integrin alpha 6 beta 1, providing the basis for the development of peptide mimetics to examine the functional role of alpha 6 beta 1 in angiogenesis.

Alanine↗

PubMed2003

Regulation of 11 beta-hydroxysteroid dehydrogenase enzymes in the rat kidney by estradiol.

The 11beta-hydroxysteroid dehydrogenase (11betaHSD) type 1 (11betaHSD1) enzyme is an NADP+-dependent oxidoreductase, usually reductase, of major glucocorticoids. The NAD+-dependent type 2 (11betaHSD2) enzyme is an oxidase that inactivates cortisol and corticosterone, conferring extrinsic specificity of the mineralocorticoid receptor for aldosterone. We reported that addition of a reducing agent to renal homogenates results in the monomerization of 11betaHSD2 dimers and a significant increase in NAD+-dependent corticosterone conversion. Estrogenic effects on expression, dimerization, and activity of the kidney 11betaHSD1 and -2 enzymes are described herein. Renal 11betaHSD1 mRNA and protein expressions were decreased to very low levels by estradiol (E2) treatment of both intact and castrated male rats; testosterone had no effect. NADP+-dependent enzymatic activity of renal homogenates from E2-treated rats measured under nonreducing conditions was less than that of homogenates from intact animals. Addition of 10 mM DTT to aliquots from these same homogenates abrogated the difference in NADP+-dependent activity between E2-treated and control rats. In contrast, 11betaHSD2 mRNA and protein expressions were significantly increased by E2 treatment. There was a marked increase in the number of juxtamedullary proximal tubules stained by the antibody against 11betaHSD2 after the administration of E2. Notwithstanding, neither the total corticosterone and 11-dehydrocorticosterone excreted in the urine nor their ratio differed between E2- and vehicle-treated rats. NAD+-dependent enzymatic activity in the absence or presence of a reducing agent demonstrated that the increase in 11betaHSD2 protein was not associated with an increase in in vitro activity unless the dimers were reduced to monomers.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗

PubMed2003

Direct observations of the cleavage reaction of an L-DPPC monolayer catalyzed by phospholipase A2 and inhibited by an indole inhibitor at the air/water interface.

The enzymatic hydrolysis of an L-dipalmitoylphosphatidylcholine (L-DPPC) monolayer at the air/water interface, catalyzed by phospholipase A(2) (PLA(2)), serves as a model for biospecific interfacial reactions. The cleavage of L-DPPC was investigated by Brewster angle microscopy. Different types of domain defects were observed to form in the coexisting liquid expanded and liquid condensed phases during the hydrolysis reaction. The adsorption of the enzyme was quantitatively recorded as the increase of the surface pressure over a fixed molecular area with time. In the case of L-DPPC, the surface pressure first increases and then starts to decrease, which indicates that a soluble product (lysolipid) is produced during the catalytic cleavage reaction. The increase and decrease of the surface pressure, which corresponds to the change of shape and number density of domains, indicated the occurrence of the following processes: adsorption of PLA(2), cleavage reaction, and rearrangement of substrate and product molecules at the interface. Addition of a PLA(2) inhibitor to the lipid monolayer leads to a fast surface pressure increase after enzyme injection. The surface pressure reaches a maximum value and then does not change for a long time. During this period, no change in the domain shape and number density was observed, which indicates that the enzyme is inhibited for a certain period of time. The experimental results provide the possibility of a direct way to prove inhibitor activity.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2003

Effects of repeated stress on regeneration of serotonergic and noradrenergic axons in the cerebral cortex of adult rats.

We examined whether regeneration of serotonergic (5-HT) and noradrenergic (NA) axons might be affected by stress. Neurotoxins to 5-HT or NA axons were injected into the frontal cortex to cause partial denervation. Mild restraint stress (40 min/day) was started 16 days later and given for 14 consecutive days (30-day stressed group). Non-stressed animals were divided into two groups, animals sacrificed at 14 days (14-day control group) and those sacrificed at 30 days (30-day control group) after the toxin injection. In immunohistochemical study, the denervation area of 5-HT axons but not that of NA axons was significantly smaller in the 30-day control group than in the 14-day control group. However, there was no significant difference between the 14-day control and 30-day stressed groups. These findings suggested that regeneration of 5-HT axons occurred earlier than that of NA axons, and that stress exerted inhibitory influence on regeneration of 5-HT axons.

Animals↗